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Starting system issues

Been having Issues with a Prentice 2670 . If the machine sits for more than 1 day it will not start without a boost. I have noticed while attempting to diagnose the problem that I have 10.75 volts at the negative terminal, 1.68 volts at the positive terminal and about 12.48 across both terminals. Why does my negative terminal have voltage? What is the best way to diagnose and fix this issue?

New stereo but had this issue before then. I am the 2nd owner and it has had this issue since I have owned it. Starts fine if machine is used every day, otherwise have to boost. Below 20°F will also need boost.

Those measurements are meaningless, you want to know running volts from terminal to terminal, and alternator + to machine frame.

Below 20 needing a boost can be any number of things, way too complicated to start with that.

If you leave it sit a week, will it crank the same as the next day, or completely dead? How does it crank the next day after it's run for an hour or more? Like Kshansen said, disconnect the ground after running it for an hour or more, and see if it will CRANK OK a week later, if it won't then the battery is weak, or you have other starter issues. If it cranks the same at first but just doesn't start before the battery tires out, then you have other issues.

There is a battery disconnect. Batteries are disconnected at the end of day via disconnect switch. Battery is dead after sitting more than 1 day. I can also put the battery on a 2amp automatic charge cycle and the charger will never indicate battery is full. I have tried using different chargers with the same results. What about battery cables? What would I be looking for if I check resistance?

It doesn't matter if there's a disconnect. remove one cable from the battery, and see if it will start the next day. We're trying to see if the battery will hold a charge when disconnected from the machine. Or replace the battery...

You can do simple parasitic amp draw test with LED test light ( incandescent will not work with small current draw ), take the negative clamp off of battery post, connect one lead to post another toclamp - if you see the light with disconnect off - you have a draw. You can do the same with multimeter switched to amp reading but most multimeters have fuses 400-500 milliamperes, well if you burn the fuses it will mean you have parasitic amp draw over fuse limit.

It doesn't matter if there's a disconnect. remove one cable from the battery, and see if it will start the next day. We're trying to see if the battery will hold a charge when disconnected from the machine. Or replace the battery...

Click to expand...

If the battery wet on top and get pretty warm or even hot at the end of the day - it is shorted.

Sounds like a parasitic draw. Test your negative lead like you have earlier when found voltage on it. Then start pulling fuses one at a time until you see the voltage go away. What ever that fuse is protecting is draining your battery.

Lol.. THATS how "I" find them too Paul.
I figured he had a dead battery at post #5.. if u have a disconnect, that means there isn't a draw?? the battery is discharging itself..??
Its funny how "more information" comes out the more they write..
Post #5 should have been included in post #1..

Thanks for your help guys. I do have a cable that is in bad shape also. The insulation has been oil soaked and swelled. Looks like i had a little fire in the machine also. Building new cables and then I will install the new battery and give it a whirl.